Pre-Emergence Herbicides and Mulches for Weed Control in Cutting Propagation

Weed control is critical in cutting propagation to maximize root growth and liner quality, but hand weeding is time consuming and not cost efficient. Pre-emergence herbicides are widely used in container-grown nursery crop production, but concerns of potential phytotoxicity have limited widespread use in propagation. Mulches are a viable alternative for weed control but few products have been evaluated in propagation. Five pre-emergence herbicides and five mulches were evaluated for rooting stem cuttings of three nursery crop species and for control of four weed species. Mulches were applied (0.8 cm depth) prior to sticking cuttings while pre-emergence herbicides were applied (low labeled rate) two weeks after sticking cuttings. Rooting percentage, root dry weight, and shoot dry weight were not affected by pre-emergence herbicide or mulch, except for butterfly bush (Buddleja davidii'Nanho Blue') which was severely injured when treated with the pre-emergence herbicide isoxaben. Oxyfluorfen + oxadiazon provided excellent control of all tested weed species and has potential to be used in propagation of a number of crops. Mulches did not provide adequate weed control, but increased application depth may enhance efficacy and should be further evaluated.